1. Field of the Invention
The present invention relates to a fluidizing apparatus and more particularly to a fluidizing apparatus of the type in which gas is used as a fluidizing medium.
2. Description of the Prior Art
As is well known, a gas distribution plate, such as a perforated plate, is provided at a predetermined position in a vessel constituting a fluidizing apparatus, for instance at the lower end of the vessel, and the interior of the vessel is divided into two chambers, upper and lower chambers, by the gas distribution plate. The lower chamber is provided with piping connected thereto, and gas introduced into the lower chamber through the piping flows through the gas distribution plate so that a fluidized bed is formed in the upper chamber.
In one type of conventional fluidizing apparatus, the gas distribution plate is typically supported in the vessel by placing its peripheral edge on a plurality of projections projecting inward from the inner wall surface of the vessel. In another conventional fluidizing apparatus, the vessel is separated into two halves, an upper half and a lower half, at the level at which the gas distribution plate is provided, so that it is firmly held between the upper and lower halves when they are assembled.
However, a problem inherent to these conventional fluidizing apparatus is that the gas distribution plate cannot support the heavy weight of the fluidized bed formed above it. For this reason, conventional fluidizing apparatuses are limited to a certain specific type, for instance a small type.
To resolve this problem, another conventional fluidizing apparatus is constructed such that beam-shaped support members are arranged in the form of lattice across the interior of the vessel, so as to carry the gas distribution plate. However, it has been found that this type of conventional fluidizing apparatus tends to cause the deposition of powder, grains, or similar fine particles carried by the fluidizing gas on the support members, at the corners where they come into contact with the gas distribution plate, and the bottom surface thereof, when the fluidizing gas introduced into the lower chamber contains powdery materials. As the fluidizing apparatus continues operating, the volume of unwanted fine particles deposited thereon increases gradually, until a number of the holes in the gas distribution plate are clogged with the fine particles.
When the gas distribution plate has clogged holes, the fluidization gas passing therethrough is reduced, so that it becomes still or irregular in the fluidizing bed. As a result, grain, granular material or the like in the fluidizing bed coheres each other and becomes clods on the gas distribution plate, which forces the fluidizing apparatus to stop operating.